Malheur Experiment Station Information for Sustainable Agriculture

Potato Variety Trials 2004

Eric P. Eldredge, Clinton C. Shock, and Lamont D. Saunders

Malheur Experiment Station

Oregon State University

Ontario, OR

Introduction

New potato varieties were evaluated for their productivity and usefulness for processing. Potatoes are grown under contract in Malheur County, Oregon for potato processors to produce frozen products for the food service industry. There is very little production for fresh pack or open market, and very few growers have potato storage buildings on their farms. There is also no production of varieties for making potato chips. Potato seed is not produced in Malheur County because high populations of aphids result in virus infection in the tubers.

The varieties grown for processing are mainly 'Ranger Russet', 'Shepody', and 'Russet Burbank'. Harvest begins in July, and potatoes go to processing plants directly from the field. Yields are limited by "early die" syndrome, which causes early senescence of the vines. Early die is caused by a complex of soil pathogens, including bacteria, nematodes, and fungi, and is worse when crop rotations between potato crops are short.

Small acreages of new varieties or advanced selections are sometimes contracted to study the feasibility of expanding their use. To displace an existing processing variety, a new potato variety needs to have several outstanding characteristics. The yield should be at least as high as the yield of Russet Burbank. The tubers need to have low reducing sugars for light, uniform fry color, and high specific gravity. A new variety should be resistant to tuber defects or deformities caused by disease, water stress, or heat. It should begin tuber bulking early if it is a variety for early harvest. Or, if it is a late-harvest variety, it should be resistant to early die.

Potato variety development trials at Malheur Experiment Station (MES) in 2004 included the Western Regional Early Harvest Trial with 20 entries, the Western Regional Late Harvest Trial with 20 entries, the Oregon Statewide Trial with 29 entries, the Oregon Preliminary Yield Trial with 131 entries, a Malheur Preliminary Yield Trial of 6 strains selected in previous 8-Hill trials at MES, and an 8-Hill trial of 84 clones from the USDA Agricultural Research Service (ARS) potato breeding program at Aberdeen, Idaho. Through these trials and active cooperation with other scientists in Idaho, Oregon, and Washington, promising new lines are bred, evaluated, and eventually released as new varieties.

Materials and Methods

Six potato variety trials were grown under sprinkler irrigation on Owyhee silt loam, where winter wheat was the previous crop in a potato, wheat, corn, wheat, potato rotation. The wheat stubble was flailed and the field was irrigated and disked. A soil test taken on September 16, 2003 showed 37 lb nitrogen (N)/acre in the top 2 ft of soil, and 102 lb available phosphate (P₂O₅), 851 lb soluble potash (K₂O), 29 lb sulfate (SO₄), 1966 ppm calcium (Ca), 463 ppm magnesium (Mg), 87 ppm sodium (Na), 1.6 ppm zinc (Zn), 18 ppm iron (Fe), 4 ppm manganese (Mn), 0.7 ppm copper (Cu), 0.5 ppm boron (B), organic matter 3.5 percent, and pH 7.4 in the top foot of soil. Fall fertilizer was spread to apply 60 lb N/acre, 50 lb P₂O₅/acre, 80 lb K₂O/acre, 57 lb sulfur (S)/acre, 8 lb Zn/acre, 5 lb Cu/acre, and 1 lb B/acre. The field was ripped, Telone II^® soil fumigant was injected at 25 gal/acre, and the field was bedded on 36-inch row spacing.

Seed of all varieties was hand cut into 2-oz seed pieces and treated with Tops-MZ^®+ Gaucho^® dust one to two weeks before planting and placed in storage to suberize. On March 22, 2004, the field was cultivated with a Lilliston rolling cultivator to reshape the hills and to control winter annual weeds and volunteer wheat. On April 2 a soil sample was taken that showed 43 lb N/acre in the top 2 ft of soil, 83 lb available P₂O₅, 688 lb soluble K₂O, 26 lb SO₄, 1,835 ppm Ca, 353 ppm Mg, 69 ppm Na, 1.1 ppm Zn, 5 ppm Fe, 1 ppm Mn, 0.4 ppm Cu, 1.2 ppm B, pH 7.4, and 3.0 percent organic matter in the top foot of soil.

Potato seed pieces were planted in single-row plots using a 2-row cup planter with 9-inch seed spacing in 36-inch rows. Red potatoes were planted at the end of each plot as markers to separate the potato plots at harvest. After planting, hills were formed over the rows with the Lilliston rolling cultivator. Prowl^® at 1 lb/acre plus Dual^® at 2 lb/acre herbicide was applied as a tank mix for weed control on May 7 and was incorporated with the Lilliston. Matrix^® herbicide was applied at 1.25 oz/acre on May 17 and was incorporated with 0.41 inch of rain on the next day, followed by 0.89 inch of additional rain through the end of May.

The Western Regional Early Harvest Trial was planted on April 13, 2004. The Western Regional Late Harvest and the 8-Hill Trial were planted on April 19. The Statewide Trial and the Preliminary Yield Trials were planted on April 26. The Malheur Preliminary Yield Trial, planted on April 26, consisted of 2 entries with sufficient seed available to plant 4 replicates of 30 seed pieces, and 4 entries with enough seed available to plant 2 replicates of 20 seed pieces. The 8-Hill trial was unreplicated with plots 8 seed pieces long, the Oregon Preliminary Yield Trial had 2 replicates with plots 20 seed pieces long, and the Statewide, Western Regional Early Harvest, and Western Regional Late Harvest Trials each had 4 replicates with plots 30 seed pieces long.

Irrigation was applied 21 times (Fig. 1), from June 4 to August 30, with scheduling based on soil water potential. The average readings of 6 Watermark soil moisture sensors (model 200 SS, Irrometer Co. Inc., Riverside, CA) were monitored every 8 hours by a Hansen model AM400 datalogger (M. K. Hansen Co., East Wenatchee, WA). Sensors were installed in the potato row at the seedpiece depth, 10 inches from the top of the hill. The AM400 unit was read frequently through the summer to predict crop water needs; the objective was to apply an irrigation just before the average soil moisture in the potato root zone at the seedpiece depth reached -60 kPa (Fig. 2). Water applied was estimated by recording the sprinkler set duration at 55 psi, and using the nominal sprinkler head output. Crop evapotranspiration (ET_c) was estimated by the U.S. Bureau of Reclamation based on data from an AgriMet weather station at MES.

Fungicide applications to control early blight and prevent late blight infection started with an aerial application of Ridomil Gold^® and Bravo^® at 1.5 pint/acre on June 12. On June 25, Headline^® fungicide was applied; on July 17, Topsin-M^® fungicide plus liquid sulfur with 1.5 lb P₂O₅/acre and 0.2 lb Zn/acre was applied by aerial applicator. On August 8, Headline plus 6 lb S/acre was applied to prevent two-spotted spider mite infestation and powdery mildew infection.

Petiole tests were taken every 2 weeks from June 14, and fertilizer was injected into the sprinkler line during irrigation to supply the crop nutrient needs. A total of 103 lb N/acre, 44 lb P₂O₅/acre, 140 lb K₂O/acre, 100 lb SO₄/acre, 0.3 lb Mn/acre, 5 lb Mg/acre, 0.1 lb Cu/acre, 0.1 lb Fe/acre, and 0.5 lb B/acre were applied.

Vines were flailed in the Western Regional Early Harvest Trial on August 16. Western Regional Early Harvest Trial potatoes were lifted August 27 with a two-row digger that laid the tubers back onto the soil in each row. Visual evaluations included observations of desirable traits, such as a high yield of large, smooth, uniformly shaped and sized, oblong to long, attractively russetted tubers, with shallow eyes evenly distributed over the tuber length. Notes were also made of tuber defects such as growth cracks, knobs, curved or irregularly shaped tubers, pointed ends, stem-end decay, stolons that remained attached, folded bud ends, rough skin due to excessive russetting, pigmented eyes, or any other defect, and a note to keep or discard the clone based on the overall appearance of the tubers.

Tubers were placed into burlap sacks and hauled to a barn where they were kept under tarps until grading. After grading, a 20-tuber sample from each plot in the Western Regional Early Harvest Trial was evaluated for tuber quality traits for processing. Specific gravity was measured using the weight-in-air, weight-in-water method. Ten tubers per plot were cut lengthwise and the center slices were fried for 3.5 min in 375°F soybean oil. Percent light reflectance was measured on the stem and bud ends of each slice using a Photovolt Reflectance Meter model 577 (Seradyn, Inc., Indianapolis, IN), with a green tristimulus filter, calibrated to read 0 percent light reflectance on the black standard cup and 73.6 percent light reflectance on the white porcelain standard plate.

The vines were flailed on the late harvest trials on September 21. The vines of most entries had died by the date of the last irrigation on August 30. Potatoes in the Western Regional Late Harvest Trial were dug on October 5. The 8-Hill Trial tubers and the potatoes in the Statewide Trial were dug on October 6-7, and the Preliminary Yield Trial tubers were dug on October 7-8. At each harvest, the potatoes in each plot were visually evaluated as described above. Tubers were graded and a 20-tuber sample from each plot was placed into storage. The storage was kept near 90 percent relative humidity and the temperature was gradually reduced to 45°F. Tubers were removed from storage November 19 through December 6 and evaluated for tuber quality traits, specific gravity, and fry color as described above. Data were analyzed with the General Linear Models analysis of variance procedure in NCSS (Number Cruncher Statistical Systems, Kaysville, UT) using the Fisher's Protected LSD means separation t-test at the 95 percent confidence level.

Results and Discussion

At the Malheur Experiment Station in 2004, spring weather was cool and wet, followed by a summer without the usual extreme heat. Dry weather prevented late blight from developing in 2004. No powdery mildew or mite problems were observed in the field. Compared to the 2003 potato trials at this location, overall yields were lower by about 17 percent, and specific gravity of the tubers was lower.

Precipitation during May 1 through September 30 was 2.55 inches, the crop evapotranspiration (ET_c) for the late-harvest trials totaled 26.19 inches, and the trials received 22.15 inches of irrigation plus precipitation, or 84.6 percent of ET_c (Fig. 1). The step increases in the irrigation plus rainfall curve show the 21 sprinkler irrigations applied during the growing season.

The trend of soil moisture during the growing season is shown in Figure 2. The data do not show the individual irrigations because the sensors did not always respond to an irrigation. The irrigation plus rainfall was less than ET_c for the growing season, and the sensor data show that average root zone soil water potential became drier than -60 kPa at least four times during the growing season.

Soil water potential at the seedpiece depth was allowed to become drier than -60 kPa at the end of the growing season, after the vines died on the early maturing entries, by applying frequent sprinkler irrigations of short duration, as shown in Figure 1. This was necessary to avoid swollen lenticels and the associated possibility of rotting the tubers of the early entries, while continuing to apply a portion of the ET_c requirement for the late maturing entries in shallow moisture increments.

Western Regional Early Harvest Trial

In the Western Regional Early Harvest Trial, among the highest in total yields were 'A92294-6', 'Shepody', 'AC93026-9Ru', 'A93157-6LS', and 'TC1675-1Ru' with total yield ranging from 473 to 546 cwt/acre (Table 1). Of those clones, only TC1675-1Ru had specific gravity above 1.080 g cm^-3, a desirable level for processing. In production of marketable tubers for processing (the total of U.S. No.1 plus U.S. No. 2 grades), A92294-6, Shepody, AC93026-9Ru, A9305-10, TC1675-1Ru, and A93157-6LS with marketable yield from 423 to 499 cwt/acre were among the highest in marketable yield.

Western Regional Late Harvest Trial

The highest total yield In the Western Regional Late Harvest Trial was produced by A92294-6, with 658 cwt/acre, and it also produced the highest marketable yield, 632 cwt/acre (Table 2). Among the highest producers of U.S. No. 1 tubers, on a percentage basis, were 'AC92009-4Ru', 'ATX91137-1Ru', and 'AO96160-3', with ATX92230-1Ru, 'Russet Norkotah', and 'A95109-1', ranging from 84 to 94 percent. Among the highest total U.S. No. 1 tuber producers were ATX92230-1Ru, A93157-6LS, AO96160-3, A92294-6, A9305-10, 'A95074-6', and TC1675-1Ru, ranging from 377 to 437 cwt/acre. Shepody, A92294-6, and Russet Burbank produced significantly more U.S. No. 2 tubers than other clones in this trial. In this late-harvest trial, specific gravity of A93157-6LS, AC92009-4Ru, AO96160-3, Ranger Russet, A92294-6, A95074-6, and TC1675-1Ru were among the highest, and acceptable for processing into frozen potato products.

Oregon Statewide Trial

In the Oregon Statewide Trial, the six clones marked with an asterisk were retained by the variety selection committee (Table 3). The clone AO96160-3 will stay in the Statewide Trial and in the Western Regional Trial, 'AO96164-1' will advance to the Western Regional Trial, 'AO96141-3' and 'AO98133-2' will advance to the Western Regional Russet Early and Late Harvest Trials, and 'AO96162-1' and 'AO99099-3' will be maintained in the Statewide Trial in 2005. At this location in 2004, AO96160-3, AO96164-1, AO96141-3, AO98133-2, AO96162-1, and AO99099-3 produced among the highest total yields, with a high percentage of U.S. No. 1 tubers, good specific gravity for processing, and light fry colors with no sugar ends. Russet Burbank produced 102 cwt/acre U.S. No. 2 tubers, significantly more than any other entry, and had 30 percent sugar ends.

Oregon Preliminary Yield Trial

In the Preliminary Yield Trial, 126 numbered clones were compared to Russet Burbank, Ranger Russet, Shepody, Russet Norkotah, and 'Umatilla Russet' (Table 4). The Oregon potato variety selection committee kept 11 clones, based on their performance at Hermiston, Klamath Falls, Powell Butte, and Ontario, to advance to the Statewide Trial for 2005. The clones that were advanced were 'AO96305-3' , 'AO96365-2', 'AO96370-2', 'AO98123-2', 'AO98268-5', 'AO98282-5', 'AO98307-6', 'AO99065-2', 'AO99081-1', 'AO99108-5', and 'AO99111-9'. These clones yielded well across the four locations (Hermiston, Klamath Falls, and Powell Butte data are not shown in this report), had a low incidence of undesirable characteristics, had high percentage of U.S. No. 1 tubers, and if selected as promising clones for processing, had high specific gravity, light fry color, and resistance to developing sugar ends in response to stress.

Malheur Preliminary Trial

This was the first year of a Malheur Preliminary Trial, a cooperative project by the Malheur Agricultural Experiment Station and the USDA-ARS. Six clones from previous 8-Hill trials at Malheur were selected for their adaptation to the high early die pressure, heavy soil texture, and hot, dry climate of the Treasure Valley. These clones were compared to Russet Burbank, Ranger Russet, and Umatilla Russet (Table 5). The clones 'A98345-1', 'A91814-2', 'A96112-20', produced a high percentage of U.S. No. 1 tubers, had specific gravity above 1.080 g cm^-3 (a level desirable for processing), and produced no sugar ends. The clones 'A99133-6' and 'A99123-1' each produced 5 percent sugar ends, and 'A96783-109LB', produced 15 percent sugar ends.

8-Hill Trial

Eight hills were grown of each of 84 clones selected for long, russet tubers from the Aberdeen ARS potato breeding program, including 17 clones with the LB suffix signifying that they were bred for resistance to late blight. The 84 clones were evaluated for tuber type, yield, grade, and processing quality (Table 6). Yield and grade data were examined for clones having total yield greater than 530 cwt/acre and U.S. No. 1 tubers at 93 percent or higher, without excessive U.S. No. 2, cull, or undersized (less than 4 oz) tubers. Twenty-six of the clones had high yields and produced a high percentage of U.S. No. 1 tubers. Samples of these clones were analyzed for processing quality. The clone 'COA00329-1' yielded a total of 695 cwt/acre, with 85 percent U.S. No. 1 tubers, specific gravity of 1.092 g cm^-3, and an average fry strip light reflectance of 47.8 percent, which was acceptable for processing, with 0 percent sugar ends. The clone 'A00345-3LB' yielded 644 cwt/acre total, with 91 percent U.S. No. 1 grade, specific gravity 1.085 g cm^-3, and fry strip light reflectance of 44.5 percent.

Figure 1. Crop evapotranspiration (ET_c) and sprinkler irrigation applied (plus rain) to potato variety trials, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Figure 2. Soil moisture data for sprinkler-irrigated potato variety trials, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Table 1. Yield, grade, and processing quality of potato entries grown in the Western Regional Early Harvest Trial at Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

^†NS= Not significant.

Table 2. Yield, grade, and processing quality of potato entries grown in the Western Regional Late Harvest Trial at Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

^†NS = Not significant.

Table 3. Yield, grade, and processing quality of potato entries grown in the Oregon Statewide Trial at Malheur Experiment Station, Oregon State University, Ontario, OR, 2003.

Table 4. Yield, grade, and processing quality of 11 early selections from the 131 entries in the Oregon Preliminary Yield Trial, compared to the 5 check entries, Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

Table 5. Yield, grade, and processing quality of early selections from the Malheur Preliminary Trial (in bold) compared to several check entries grown at Malheur Experiment Station, Oregon State University, Ontario, OR, 2004.

^†Statistics based on 135 entries.

^‡ NS = Not significant. Table 6. Yield, grade, and processing quality for 26 selections from 84 potato clones entered in an unreplicated 8-Hill Trial at Malheur Experiment Station, Oregon State University, 2004.

^†Means based on 84 entries.

^‡ Means based on 26 entries.

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Last updated  Monday August 30, 2010 .